Officials and Drone Enthusiasts Are Still Puzzling Over Exactly What Happened

Weeks after a federal regulator first publicly described a near miss between a drone and an airliner, officials and drone enthusiasts are still puzzling over exactly what happened, a mystery that illustrates the challenges in tracking unmanned aircraft in U.S. skies.

A Federal Aviation Administration official said on May 8 that an American Airlines Group Inc. jet in March nearly hit a model aircraft around 2,300 feet above...